Inborn Errors of Immunity and Autoimmune Disease.

Abstract

Autoimmunity may be a manifestation of inborn errors of immunity (IEI) specifically as part of the subgroup of primary immunodeficiency (PID) known as primary immune regulatory disorders (PIRD). However, while making a single gene diagnosis can have important implications for prognosis and management, picking patients to screen can be difficult, against a background of a high prevalence of autoimmune disease in the population. This review compares the genetics of common polygenic and rare monogenic autoimmunity, and explores the molecular mechanisms, phenotypes and inheritance of autoimmunity associated with PIRD, highlighting the emerging importance of gain-of-function and non-germline somatic mutations. A novel framework for identifying rare monogenic cases of common diseases in children is presented, highlighting important clinical and immunological features that favor single gene disease and guides clinicians in selecting appropriate patients for genomic screening. Additionally, there will be a review of autoimmunity in non-genetically defined PID such as common variable immunodeficiency (CVID), and of instances where primary autoimmunity can result in clinical phenocopies of IEI.